Perm Journal of Petroleum and Mining Engineering (Sep 2015)
Computational scheme of evaluating strain-stress state of piecewisehomogeneous three-dimensional elastic environment based on indirect method of boundary elements
Abstract
Finite-element techniques in geomechanic calculations to assess strain-stress state in rock have shown insufficient flexibility towards varying geometry of computational schemes and necessity to set a large number of the unknown in solving space problems. Numeric calculation of stress intensity factor at the fracture tip by finite element analysis is a very demanding task in dimensional geomechanic simulation. Domain partition by irregular grid significantly expands the length of rigidity matrix bandwidth, which also largely depends on element enumeration approach. When computational scheme geometry considerably exceeds the size of the area of the detailed exploration of strain-stress state application of traditional methods of finite elements and geometric immersion is not feasible. The paper suggests to apply a potentially more accurate computational scheme for assessing strain-stress state of three-dimensional piecewise-homogeneous elastic environment on the basis of indirect method of boundary elements. In developing potassium beds by pillar system displacement discontinuity method as a variation of boundary element method appears to be a convenient tool to compute strain-stress state, which allows taking account of relation between the top and soil of the longwall space. Based on the indirect method of boundary elements, a software package was developed that offers a computational scheme to solve the problem of evaluating strain-stress state of piecewise-homogeneous linear-elastic environment. The results of solving test problems are given that prove adequacy of the computational scheme to evaluate strain-stress state of rock.
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